Profile of cytokine production during the inhibition of acute xenograft rejection.

: Th2 cells have been shown to exert cell-mediated immune responses in vitro; therefore, the present study was conducted to investigate the cellular mechanisms of the long-term survival of cardiac xenografts by measuring cytokine production from recipient lymphocytes. Xenogeneic heart grafts from Lewis rats were transplanted into C57BL/6 mice, and the recipients were intravenously injected with H57-597 at the time of transplantation. The production of Th1 cytokines, namely, interleukin (IL)-2 and interferon (IFN)-gamma, and Th2 cytokines, namely, IL-4 and IL-10, from mixed lymphocyte culture cells was assayed by enzyme-linked immunosorbent assay. Splenocytes from the xenograft recipients treated with H57-597 produced significantly lower levels of IL-2, IFN-gamma, IL-4, and IL-10 than those from the untreated recipients, 100 days after transplantation. The findings of this study indicate that the long-term survival of cardiac xenografts induced by H57-597 is mediated by the inhibition of Th0, or both the Th1 and Th2 response.